A260408 Bisection of A260310.

3, 7, 11, 7, 17, 29, 41, 53, 31, 71, 29, 107, 61, 41, 131, 53, 157, 113, 179, 239, 131, 79, 73, 127, 127, 229, 223, 113, 199, 73, 317, 181, 43, 269, 241, 89, 193, 101, 89, 211, 331, 167, 313, 409, 97, 113, 401, 480, 193, 109, 457, 241, 431

Offset

1,1

Comments

Lesser (member) of the n-th pair in A260310.

Most of the terms are prime, 97.25%, but there are composites, 2.75%: 480, 960, 990, 1200, 1170, 1950, 1890, 2610, ..., . They seem to all be congruent 0 (mod 6).

Conjecture: when a(n) is prime, A260409(n) is composite and vice versa. No contradictions in the first 10000 terms.

A260408 sorted without repeats: 3, 7, 11, 17, 29, 31, 41, 43, 53, 61, 71, 73, 79, 89, 97, 101, ..., .

Primes that have not appeared yet (10000 terms examined): 2, 5, 13, 19, 23, 37, 47, 59, 67, 83, 103, 139, 151, 163, 191, 197, ..., .

Links

Robert G. Wilson v, Table of n, a(n) for n = 1..9906

Formula

a(n) = A260310(2n-1).

Example

See A260310.

Mathematica

(* first run the Mmca in A260310 and then *) Take[ Transpose[ lst][[1]], 75]

Crossrefs

Cf. A260310, A260409, A260410.

Sequence in context: A335980 A153788 A167486 * A261103 A262505 A083754

Adjacent sequences: A260405 A260406 A260407 * A260409 A260410 A260411

Keyword

nonn

Author

Robert G. Wilson v, Jul 24 2015

Status

approved